MATLAB: Find intersection point given a line segment

line fitting

Hi I have the given image of a curve where the two points (blue crosses) are joint with a line and would like to know where this line would cross the x axis (see green line and point in blue circle).

Thanks in advance

Best Answer

Since it appears to be a linear regression, defined as:

y = slope * x + y_intercept;

the x-axis intercept (where y=0) would be:

x_intercept = -y_intercept / slope;

If you want to know where it intersects y=0.2,

x_intercept = (0.2 - y_intercept) / slope;

Related Solutions

MATLAB: Intersection of line and curve from thier points

Try this:

x_line = [7020 0];
y_line = [0 250000];
x_curve = [5620 4850 4290 3600];
y_curve = [0 100000 200000 300000];
b_line = polyfit(x_line, y_line,1);                     % Fit ‘line’
y_line2 = polyval(b_line, x_curve);                     % Evaluate ‘line’ At ‘x_curve’
x_int = interp1((y_line2-y_curve), x_curve, 0);         % X-Value At Intercept
y_int = polyval(b_line,x_int);                          % Y-Value At Intercept
figure(1)
plot(x_line, y_line)
hold on
plot(x_curve, y_curve)
plot(x_int, y_int, '+r')                                % Plot Intercept Point
hold off

MATLAB: Is the equation of the line of best fit incorrect

Your graph doesn't show the y-intercept. The x-axis range starts at 1900, rather than zero.

Best Answer

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MATLAB: Intersection of line and curve from thier points

MATLAB: Is the equation of the line of best fit incorrect

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